Method
A total of 17,496 patients who underwent catheter ablation of AF for the first time in Beijing Anzhen Hospital from January 2015 to December 2021 were screened. The inclusion criteria were (1) aged 18 years or older; (2) diagnosed with AF; (3) history of mitral valve replacement. The exclusion criteria were a history of catheter ablation, surgical maze procedure, left atrial appendage closure or resection. A total of 68 patients who met the inclusion and exclusion criteria were enrolled in the study. According to the type of MVR, the patients were divided into two groups: the bioprosthetic MVR group and the mechanical MVR group. Totally, 12 patients were enrolled in the bioprosthetic MVR group and 56 patients in the mechanical MVR group. Written inform consents were obtained in all the patients prior to the ablation procedure. The study was approved by the institute ethics committee.
Catheter ablation of AF
All anti-arrhythmic drugs except amiodarone were discontinued for at least 5 half-lives before catheter ablation. The procedure was performed under fasting, conscious sedation and uninterrupted anticoagulation. During the procedure, heparin was injected intravenously to maintain the activated clotting time at 300-400s. AF ablation strategy was described previously9. The left atrium geometry was reconstructed in the CARTO system, with a 3.5 mm tip ablation catheter point by point (Navi-Star Thermocool, or Thermocool-Smart-touch Biosenes Webster, USA) (2015-2018) or PentRay Nav eco tip catheter (Biosenes Webster, USA) with fast anatomy mapping (Since 2018). The patients with paroxysmal AF were treated with circumferential pulmonary vein ablation (CPVA), the ablation endpoint is all pulmonary veins isolation (PVI). After CPVA in patients with persistent AF, LA roofline, mitral isthmus (MI), and cavotricuspid isthmus (CTI) was routinely targeted. If AF was still persistent, 200 J direct current cardioversion was performed to convert AF to sinus rhythm. Additional ablation was applied, if needed, to achieve PVI and linear block in sinus rhythm. Coronary sinus (CS), superior vena cava (SVC), fractionated potentials (CFAEs), and ligament of Marshall (LOM) were targeted at the physician’s discretion.
Data collection and follow-up
Antiarrhythmic drugs were routinely taken orally for 3 months after the procedure. The patients in the bioprosthetic MVR group were given new oral anticoagulants. The patients in the mechanical MVR group were given warfarin, targeting the international normalized ratio range of 2.0–3.0. 24h-Holter was performed monthly in the first 3 months, which was followed by 24h-Holter 6 months after the procedure and every 6 months thenceforth. Scheduled follow-up was implemented by telephone interview or outpatient follow-up to collect the occurrence of endpoint events at 3, 6, months and every 6 months thereafter. The follow-up information was collected by professionally trained follow-up personnel. If the patient had palpitations or other symptoms suggestive of arrhythmia, ECG examination was performed in the local hospital at any time.
The study endpoint was AF recurrence which was defined as any recurrence of atrial arrhythmias with a duration of ≥ 30 seconds. AF recurrence occurring within 3 months after the procedure was defined as early recurrence, and recurrence after 3 months of procedure was defined as late recurrence. If a patient underwent AF ablation again during the follow-up, the patient would not be counted in the survival analysis after the redo procedure.
Statistical analysis
SPSS 26.0 software was used for statistical analysis. All continuous variables with normal distribution were presented as mean ± standard deviation, and Independent-Samples t -test was used for comparison. Medians and quartiles were used for continuous variables with non-normal distribution, and non-parametric Mann-WhitneyU -test was used for comparison. Categorical variables were presented as numbers and proportions and compared by χ2 or Fisher’s exact test. Kaplan-Meier analysis with log-rank test was used to calculate AF recurrence-free survival between the groups. COX univariate and multivariate regression analyses were used to assess independent predictors of AF recurrence after the catheter ablation. A p -value < 0.05 was considered statistically significant.